Field patrols will soon have almost weightless solar blankets as well. These will be able to capture a once unthinkable 35pc of the sun's light as energy with thin membranes, a spin-off from technology used in satellites.

This new kit is a military imperative. Taliban ambushes of supply convoys are a major killer. The Pentagon says the cost of refueling forward bases is $400 a gallon.

The US Naval Air Weapons Station already relies on a 14 megawatt array of solar panels in California's Mojave desert for a thrid of its power. Pearl Harbour will soon follow as the Pentagon goes off-grid, better shielded from enemies.

The US Navy will derive half its energy supply from renewables by the end of this decade, according to a report entitled Enlisting the Sun: Powering the U.S. Military with Solar Energy, by the US solar industry (SEIA). It may be a stretch to say that the US Naval Research Laboratory is the vanguard of the world's green revolution, but not a big stretch.

"The US Defence Department is racing ahead. This could be like the semiconductor industry in 1980s where the military changed the game," said Jeremy Leggett, chairman of Solarcentury.

Nor is the Pentagon alone. Grant lists from the "SunShot Initiative" of the US Energy Department show that America's top research institutes are grappling with each of the key issues that have bedevilled solar energy for so long.

Los Alamos - home of the Manhattan Project - is working on smart grids and better ways to capture excess electricity produced in peak sunlight hours. The Argonne labs are working on thermal energy storage to overcome "intermittency", the curse of solar and wind.

Oak Ridge is testing coatings that increase durability of solar panels eightfold. The National Renewable Energy Laboratory is working on a CO2 power cycle that could achieve 90pc thermal efficiciency and does not require water, transforming the propects of desert solar.

The quest for renewables has quietly become a national endeavour of the world's paramount superpower, still home to 18 of the world's top 20 universities. The Japanese are no slouches either. They are spending $200m on a thermal storage project in Hokkaido using vanadium in electrolyte tanks. All this ferment will surely have consequences, though what and when is hard to predict.

The US Energy Department expects the cost of solar power to fall by 75pc between 2010 and 2020. By then average costs will have dropped to the $1 per watt for big solar farms, $1.25 for offices and $1.50 for homes, achieving the Holy Grail of grid parity with new coal and gas plants without further need for subsidies.

The current average in the US ranges from $5.30 for homes to as low as $2.50 for some utilities, though the figures are hotly disputed. Germany is further ahead, down to $2.25 to $2.50 even for homes. Broadly speaking, costs are down by a quarter over the past year due to the flood of cheap Chinese panels.

The Department expects a "nonlinear" surge in solar expansion once the key threshold is reached, "paving the way for rapid, large-scale adoption of solar electricity across the US", with solar providing 27pc of the country's power by the middle of the century. If so, solar may prove to be the bigger story than shale in the end.

"This could take off very fast and catch a lot of people by surprise. The oil and gas industry is starting to smell that renewables are really dangerous for them," said Mr Leggett.

Like all solar survivors, he has emotion invested in his dream, and the prospect of vindication is sweet. What is new is that big global banks are starting to agree. Earlier this year UBS published a report on the “unsubsidised solar revolution”, arguing that every rooftop in Italy, Spain and even Germany should have a solar cover based purely on hard economics.

"We believe the solar sector is at an inflection point," says Vishal Shah from Deutsche Bank. "It has passed the tipping point for grid parity in 10 major markets worldwide."

Deutsche Bank said the dramatic fall in the price of solar panels to between $0.60 and $0.70 per watt - lower than thought possible five years ago - has already rendered solar power competitive "without subsidies" in Japan, South Korea, Australia, Italy, Greece, Spain, Israel, South Africa, Chile, Southern California, Hawai and Chile - in some cases because electricity prices are ruinous. (Italy's solar is not efficient but electricity retails at $0.38 per kilowatt hour, compared with $0.15 in Germany and the UK).

These regions could be joined within three years by Thailand, Mexico, Argentina, Turkey and India, among others. Mr Shah said emerging markets are likely to embrace solar over the next decade for hard-headed commercial reasons, without the need for government subsidies. "Solar is now cheaper compared with diesel-based electricity generation in many markets such as India and Africa," he said.

This does not mean necessarily that Germany has benefited much from its head-long rush into solar, a decade too early for its own good. Households have been bled to subsidise the green dream. Around €100bn or more has been frittered away on costly feed-in tariffs. German investors have lost their shirts on a string of solar ventures that have gone bankrupt. The gains leaked out to copycat companies in China, able to undercut German rivals in their own market with cheap labour and giveaway credit.

Such are the perils of being a "first mover", a fate that Britain knows well. It is a reminder too that advances in solar technology do not easily translate into profits for solar companies. They are tearing each apart in cut-throat competition. Yet Germany surely did the rest us a favour by cracking photovoltaics at a crucial moment, and for that we have a debt of gratitude.

Whatever you think about that episode, it is now behind us. Solar technology is advancing on every front with the rush of history. A team at Oxford University is working on perovskite, a cheap and abundant material that may slash the costs of solar panels by 75pc to under $0.20 per watt. While normal silicon layers are 180 micrometres thick, perovskite can capture the same amount of sunlight with one micrometrr, according to MIT Technology Review.

In Australia, the University of New South Wales is probing a mix of screen-printing techniques and use of semiconductors that boost solar efficiency to 50pc. Labs in Wisconsin have found ways to undercut silicon with carbon nanotubes. That alone does not do much to lower the "soft costs" of solar installation, now the biggest barrier, but Germany's experience has shown that scale can work wonders.

The race is on: somebody, somewhere, is soon going to deliver grid parity with a clarity that silences all critics. Then we can all forget about subsidies for solar, and tax it instead, a future cash cow.

Goldman Sachs published a report last week entitled Time to renew interest in renewables?, a straw in the wind perhaps.

The message is to shun static - dare I say Luddite - assumptions about the limits of solar power. "Human ingenuity should not be underestimated," it said. Nor should the US military be underestimated.